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Double Digit

Choose two digits and arrange them to make two double-digit numbers. Now add your double-digit numbers. Now add your single digit numbers. Divide your double-digit answer by your single-digit answer. Try lots of examples. What happens? Can you explain it?

Number Detective

Follow the clues to find the mystery number.

Six Is the Sum

What do the digits in the number fifteen add up to? How many other numbers have digits with the same total but no zeros?

The Number Jumbler

Age 7 to 14
Challenge Level
Here are the instructions that the Number Jumbler asks you to follow:

Choose any two-digit number, add together both the digits and then subtract the total from your original number.

Try it a few times with some different starting numbers.
What do you notice about the answer each time?